The present invention relates to the disaggregation of asphaltenes. In particular, the present invention includes a method to determine aggregation and steps to disaggregate the asphaltenes.
Asphaltenes are a fraction of a petroleum oil or refinery process stream that typically aggregate or precipitate out of solution when a nonpolar solvent, petroleum oil, or process stream is mixed or blended with it. Asphaltenes represent a wide variety of hydrocarbon molecules that are typically polyaromatic in nature with some degree of alkylation present and which may or may not contain heteroatoms such as oxygen, nitrogen, and sulfur and metal atoms in their structures. Asphaltenes are usually found in significant quantities in heavy crude oils and refinery residua, and they are believed to sometimes self-assemble into colloidal micelle-like structures of several molecules that remain thermally suspended in solution due to their small size and possible solvating effects of other types of molecules in the petroleum oil or process stream. These micelle-like structures of several molecules are sometimes referred to as “asphaltene particles” in order to differentiate them from the single “asphaltene molecules” that may also be present in suspension in the oil. The asphaltene particles are typically smaller than twenty nanometers in size, but this can vary depending upon the source of the petroleum oil or process stream and their concentration in the oil.
It is well known that insoluble asphaltenes may precipitate when two or more unprocessed petroleum crude oils and/or refinery process streams are blended together. The term “asphaltene aggregate” refers to the formation of larger precipitated clusters of asphaltene particles and molecules that stick together due to an attractive interaction that has been introduced when the nonpolar petroleum oil and/or refinery process stream is blended into the oil containing the suspended asphaltenes. These asphaltene aggregates are typically a micron in size and are sometimes large enough to be observed with the unaided naked eye. These aggregates are also typically more dense than the surrounding oil mixture from which they precipitated, so they tend to slowly sediment. If the blending of such oils and/or process streams causes the aggregation or precipitation of asphaltenes, then the oils are said to be incompatible as opposed to compatible oils that do not precipitate asphaltenes on blending. Precipitated asphaltenes are not desirable as they are known to foul process equipment when rapidly heated to high temperatures.